import java.util.Stack;

public class MyQuece {
    //使用栈来实现队列  保持一个栈进 出交给另一个
    Stack<Integer> stack1;
    Stack<Integer> stack2;
      public MyQuece() {
          stack1=new Stack<>();
          stack2=new Stack<>();
    }

    public void push(int x) {
          stack1.push(x);
    }

    public int pop() {
          if(empty()){
              return -1;
          }
      if(stack2.isEmpty()){
          int size=stack1.size();
          for(int i=0;i<size;i++){
              stack2.push(stack1.pop());
          }
          return stack2.pop();
      }
      else {
          return stack2.pop();
      }
    }

    public int peek() {
        if(empty()){
            return -1;
        }
        if(stack2.isEmpty()){
            int size=stack1.size();
            for(int i=0;i<size;i++){
                stack2.push(stack1.pop());
            }
            return stack2.peek();
        }
        else {
            return stack2.peek();
        }

    }

    public boolean empty() {
          return stack1.isEmpty()&&stack2.isEmpty();
    }
}
